Biggs & Stratton 18Hp Vangard Stalls out

Hi All. I am running an 18 hp Vangard in an ATV, and I am having fuel/carb issues. After 30 to 60 minutes running, the engine stalls out and will barely idle. The only way to keep t running is priming through the carb. Also a quite a bit of oil is venting into the carb through a tube at the top. The flow of oil into the carb is increased noticeably by gunning the engine (when its actually running). I have changed the fuel filter and loosen the gas cap (venting) thinking this would help. Not so. Any ideas of what is going on? Desperate

 

How old is the engine?

We've got some much more knowledgeable members that will be around shortly but right now I'm wondering about the rings.

 

Thanks for the quick reply. The engine is in a 2000 BigFoot Argo ATV with 260 hours. I tried it again just now, and I can get only to move 10 ft or so in the snow, before it stalls out. Prime again and another ten feet (one mile from home to go). It will idle, but as soon as give some gas (in neutral or drive) it sputters out. It worked fine yesterday for an hour or so, but then sputtered out. I was able to limp a short distance to my trailer. The problem seems to be getting worse rapidly. There is still the oil issue come up through the vent into the carb. Could the fuel pump be my main problem here? How does it operate on this type engine?

 

Check the oil. Is it thin, overfull, and does it smell like gas?

 

I guess you are suggesting that the fuel pump may be leaking through the vacuum port into the crankcase, causing both the fuel starvation and oil venting (crankcase overfill) to the carb. Right? I will check this out. The Argo is stranded in the bush at the moment. I cannot get it to move more than ten feet between stalls. It will nor even idle now without a prime. I suppose running it on thinned oil is not good even for a short run?

 

Isn't the fuel pump a external pulse type? Not like an old style engine mounted mechanical pump. If so a carburetor issue could be causing the problem.

Yes, if the oil is heavily thinned with gas running the it for even short periods would not be a good idea.

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Almost totally off topic but I was hog hunting a few weeks ago. A guy brought his new to him Argo. When he went to back it off the trailer he went forward instead of reverse. In an instant it climbed up over the 18" high wall of the trailer and he got off the controls just as the chin of the hull was cresting the roof of his Jeep towing vehicle. Had he not gotten off the controls I'm pretty sure it would have climbed on top of the Jeep and kept going. Surprisingly there was not a scratch on the Jeep. The front mounted winch hit the spare tire on the back of the Jeep, perfectly keeping the Argo from scratching any paint. Well, once the driver figured out that he actually wanted to go back wards he just backed down off he Jeep, across the gap to the trailer and on & out like nothing had happened.

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I can't help but chuckle when I hear of your Argo stuck out in the bush. On the hunting trip a few weeks ago we had about 10 different off road vehicles. Each had it's strong and weak points. I pulled a 4 wheeler out of a deep hole with my Gator and a lot of hands were needed to load an old Max amphibious vehicle up onto the trailer. That trip really showed how helpful it can be to have buddies around to rescue you. Once we all realized that there were others around to help we got much more adventurous.

 

The oil level was high. I removed the oil (thinking gas contamination), added 5W-30, and changed the fuel pump. It started for about a 5 minute idle, and a 5 minute run in gear, then sputered out and died. Kept it going only with a prime to the carb. What are the issues to look for which affect the pulsating vacuum develo[ped in the crank case? Is there a check valve or PCV type valve that operates with the vacuum line from the crankcase?